<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>vw与vh</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        div{
            width: 100vw;
            height: 100vh;
            background-color: aqua;
        }
    </style>
</head>
<body>
    <!-- 
        vh 与 vw
        vh  view-height
        vw  view-width

        100vh === 视口的高度
        100vw === 视口的宽度

        iphone6  100vw === 375px   1vw = 3.75px
        iphone6 plus  100vw === 414px   1vw = 4.14px

        html font-size js代码动态
            font-size???vw
     -->
     <div></div>
</body>
</html>